Engine oil recirculation system for extended maintenance interval

ABSTRACT

An oil recirculation system for an internal combustion engine includes an oil sump for storage of engine oil, a supplemental oil tank configured for storage of supplemental engine oil therein, and a conduit configured to fluidly couple the supplemental oil tank and the oil sump such that supplemental engine oil from the supplemental oil tank is selectively delivered to the oil sump and engine oil is selectively extracted from the oil sump and delivered to the supplemental oil tank. The system is configured to deliver supplemental engine oil to the oil sump from the supplemental oil tank and extract engine oil from the oil sump to the supplemental oil tank during a predetermined time period.

RELATED APPLICATION DATA

This application claims priority to U.S. Provisional Application No.61/862,133 filed Aug. 5, 2013, and U.S. Provisional Application No.61/894,156 filed Oct. 22, 2013, the entire contents of which areincorporated herein by reference.

BACKGROUND

Internal combustion engine oils, used as lubricants, lose their initialqualities after extended use and are thus no longer effective. Prolongeduse causes the oil to degrade and lose its effectiveness due to anaccumulation of combustion-generated solid debris and chemicals,accumulation of frictionally-generated metallic particles and aresulting drop in viscosity.

Due to this degradation over time, engine oils must be changedperiodically. The frequency of these changes depends upon the usagepatterns of the engine-driven equipment. For example, the oil in ahomeowner's lawnmower engine may only need to be changed once perseason. On the other hand, a commercial lawnmower engine may need tohave its oil changed many times during a given season due to almostdaily use of the equipment. These frequent oil changes lead to increaseddowntime of the equipment and increased costs to the users. The size ofthe sump in the engine may be increased to allow for a greater oilcapacity (and hence greater oil life), but such an increase in size isnot practical for many lawn and garden applications.

Accordingly, it would be advantageous to have an internal combustionengine with a supplemental oil reservoir capable of recirculating oil atgiven time intervals. This supplemental oil reservoir enables increasedlife of the oil in the system and therefore increased intervals betweenoil changes.

SUMMARY

While there are a number of existing embodiments of the second type ofstick-slip piezoelectric motors where the active element is mountedtangentially to a track (FIG. 1), the present invention makes a numberof significant enhancements to the existing designs. The proposedstick-slip motor configuration improves on the manufacturability,usability, simplicity, cost and performance while significantly reducingthe size of the motor for the same force generated.

In one construction, the invention provides an oil recirculation systemfor an internal combustion engine. The system includes an oil sump forstorage of engine oil, a supplemental oil tank configured for storage ofsupplemental engine oil therein, and a conduit configured to fluidlycouple the supplemental oil tank and the oil sump such that supplementalengine oil from the supplemental oil tank is selectively delivered tothe oil sump and engine oil is selectively extracted from the oil sumpand delivered to the supplemental oil tank. The system is configured todeliver supplemental engine oil to the oil sump from the supplementaloil tank and extract engine oil from the oil sump to the supplementaloil tank during a predetermined time period.

In another construction, the invention provides an oil recirculationsystem for an engine having an oil sump that contains a first quantityof oil. The system includes a supplemental oil tank operable to containa second quantity of oil, a conduit arranged to fluidly connect thesupplemental oil tank and the oil sump, and a pump operable to at leastone of pump oil from the supplemental oil tank to the oil sump and pumpoil from the oil tank to the supplemental oil tank.

In yet another construction, the invention provides a method ofextending the life of an oil supply for an engine. The method includesproviding a first quantity of oil in an oil sump, drawing oil from theoil sump during engine operation to cool and lubricate the engine, andperiodically adding a second quantity of oil from a supplemental oiltank when the engine is not running The method further includes pumpingabout the second quantity of oil from the sump in conjunction with theaddition of oil from the supplemental oil tank to return the amount ofoil in the sump to about the first quantity.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an engine oil recirculation system inaccordance with an exemplary embodiment;

FIG. 2 is a flowchart illustrating an engine oil recirculation method inaccordance with an exemplary embodiment;

FIG. 3 is a perspective view of a mower with an engine oil exchangesystem in accordance with an exemplary embodiment;

FIG. 4 is a supplemental oil exchange system in accordance with anexemplary embodiment;

FIG. 5 is a cross-sectional view of an engine having a supplemental oilexchange system in accordance with an exemplary embodiment;

FIG. 6 is another cross-sectional view of an engine having asupplemental oil exchange system in accordance with an exemplaryembodiment;

FIG. 7 is a supplemental oil exchange system in accordance with anotherexemplary embodiment; and

FIG. 8 is another view of supplemental oil exchange system in accordancewith an exemplary embodiment shown in FIG. 7.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

DETAILED DESCRIPTION

Referring to FIG. 1, an engine oil recirculation system 100 inaccordance with an exemplary embodiment is shown. System 100 includes aninternal combustion engine 102 having a driven shaft 103. Internalcombustion engine 102 is preferably an air cooled general purposeengine, but may be any suitable oil-lubricated engine. Engine 102includes a sump or reservoir 105 containing a sufficient amount of oilfor lubrication of various components of the engine 102. As engine 102is in operation, the oil in sump 105 is splashed, sprayed, or otherwisecoated onto the components within engine 102 to lubricate and cool thosecomponents. Oil within sump 105 may be drained from engine 102 via adrain plug 107. In some embodiments, it is possible for engine 102 tohave an oil fill opening (not shown) to enable the user to change or addoil to sump 105.

Fluidly coupled to engine 102 and sump 105 is a supplemental oil tank104. Supplemental oil tank 104 is isolated from engine 102 and fluidlycoupled to sump 105 via both an oil inlet conduit 110 and an oil outletconduit 112. The locations of oil inlet conduit 110 and oil outletconduit 112 are not limited to that which is shown in FIG. 1 and may beplaced in any suitable location between supplemental oil tank 104 andsump 105. Supplemental oil tank 104 comprises a fill cap 117 that allowsfor refilling or replacement of oil in a reservoir 115 of supplementaloil tank 104. Supplemental oil tank 104 may also comprise a drain plug116 for draining of oil from reservoir 115.

Oil inlet conduit 110 enables oil contained in reservoir 115 ofsupplemental oil tank 104 to be selectively and intermittently exchangedwith the oil within sump 105 of engine 102. Prior to or concurrent withthe exchange of oil from reservoir 115 to sump 105, some or all of theoil within sump 105 is pumped or otherwise drained from sump 105 via oiloutlet conduit 112. For example, a pump 114 may be used to draw the oilout of sump 105 and into supplemental oil tank 104. This recently “used”oil from sump 105 is then mixed with a greater amount of supplementaloil within reservoir 115. A certain amount of supplemental oil fromreservoir 115 is then added to sump 105 via oil inlet conduit 110. Thissupplemental oil may be added either via a gravity feed or via anotherpump (not shown) placed in-line with oil inlet conduit 110. A floatsystem 118 may be configured to limit the amount of oil added to sump105 by cutting off the flow of oil from reservoir 115 to sump 105 oncethe oil in sump 105 reaches a predetermined level. Additionally, whilenot shown, a vent line could be included between supplemental oil tank104 and sump 105 such that the pressure levels within tank 104 and sump105 are maintained substantially equal to one another.

Exchange of oil between supplemental oil tank 104 and engine 102 ispreferably controlled by a controller 106 based on a predeterminedcondition of the engine 102 or engine operation. Controller 106 maycommunicate with pump 114, an oil inlet regulator 111, and an oil outletregulator 113 to enable the transfer of oil between reservoir 115 andsump 105 only at a certain time. Alternatively, oil inlet regulator 111and oil outlet regulator 113 may instead include one-way valvesconfigured in accordance with the flow direction desired. In accordancewith an exemplary embodiment, the transfer of oil between tanks is doneonly when the engine 102 is not in operation. Controller 106 may beconfigured to determine the operational status of engine 102 andinitiate the exchange of oil from supplemental oil tank 104 to engine102 only when engine 102 is not running Furthermore, controller 106 mayinclude a timer to initiate the oil transfer only after the engine 102has not run (i.e., has been in a non-operational state) for apredetermined period of time. In this way, heated oil may be transferredfrom sump 105 to reservoir 115 soon after engine 102 is shutdown, butnot before a predetermined amount of time has elapsed. Controller 106may also be configured to initiate the oil transfer only once per day(e.g., at night when the engine 102 will likely not be running), onceper week, etc. Alternatively, transfer of oil between reservoir 115 andsump 105 could be performed without an electronic controller 106. Thatis, the operator of engine 102 could manually initiate the transfer ofoil when engine 102 is not in use via, for example, one or more manualshut-off valves and/or a pump.

FIG. 2 is a flowchart illustrating the process of oil recirculation inaccordance with an exemplary embodiment. The process 200 begins with adetermination if the engine 102 has been shut down at 202. If no, theprocess continues to determine if the engine 102 has been shut down. Ifyes, it is determined if a predetermined time period has elapsed at 204.If no, the process continues to determine if the predetermined time haselapsed. If yes, the oil recirculation functions described above withrespect to FIG. 1 are initiated at 206. Then, at 208, it is determinedwhether either a predetermined amount of oil has been recirculated or apredetermined period of recirculation has passed. If no, the processcontinues to determine if one of these conditions exists. If yes,recirculation of oil is ended and the supplemental tank 104 and engine102 are fluidly isolated at 210.

Using the above-described oil exchange system, the intervals betweenrequired oil changes for engine 102 can be substantially increased.Also, because the supplemental oil tank 104 and engine 102 are fluidlyisolated from one another during operation of engine 102, there are nosubstantial alterations or limitations to engine 102. The system is notsusceptible to tilting, etc., as may be the case if the system were tobe fluidly coupled and in communication during certain points of engineoperation.

Referring to FIG. 3, an engine oil recirculation system in accordancewith another exemplary embodiment is disclosed. FIG. 3 shows a portionof a zero-turn radius lawnmower 300. One of ordinary skill in the artwould recognize that elements of the lawnmower have been omitted for thesake of clarity. Lawnmower 300 comprises a frame 302 having a roll-overprotection bar 304 mounted thereto. Roll-over protection systems (orROPS) are commonly used on zero-turn and large riding mowers andtractors to protect the occupant in the event that the machine tips orrolls. In the exemplary embodiment, a supplemental oil tank 308 iscoupled to or near roll-over protection bar 304 via a supplemental oiltank base 310 that is coupled to roll-over protection bar 304 or anearby portion of frame 302. Supplemental oil tank 308 is mounted uponbase 310 so as to be easily accessible by the operator or servicemechanic. As will be further described herein below, oil fromsupplemental oil tank 308 is delivered to (and/or removed from) the oilsump of engine 306 via a conduit 312. Supplemental oil tank 308 may be adedicated bottle specifically designed for the supplemental oil exchangesystem described. Alternatively, supplemental oil tank 308 may be astandard commercially-available bottle of oil, and base 310 may beconfigured so as to retain such a bottle. Regardless of the type ofbottle used, the system enables the retrofitting of existing lawnmowersand engines with a supplemental oil exchange system that does notrequire costly engine block modifications or changes to the mower frameor other components.

FIG. 4 illustrates an engine oil recirculation system in accordance withanother exemplary embodiment. System 400 comprises a bottle holder 402that serves as the base for holding a commercially-available bottle 404that contains oil. Oil bottle 404 is secured within bottle holder 402via, for example, a platform 406 and a strap 408. However, other meansof securing bottle 404 are also possible. Platform 406 may include atleast one drain hole 428 which allows water, oil, or other fluids to bedrained from the interior of bottle holder 402. Below oil bottle 404 butwithin the housing of bottle holder 402 is an electric oil pump 410. Oilpump 410 is coupled to an oil bottle conduit 412 at one inlet/outletfitting 414, wherein oil bottle conduit 412 is in fluid communicationwith the inside of oil bottle 404. The cap 430 of oil bottle 404 maycomprise a foam seal capable of preventing debris, water, etc. out ofthe interior of oil bottle 404, yet not creating a “sealed” system. Withthis configuration, oil bottle 404 is not susceptible to temperaturefluctuations causing the formation of a vacuum or leading to siphoningeffects in the system. Oil bottle conduit 412 extends beyond cap 430 andinto the interior of oil bottle 404. Conduit 412 may extend to thebottom of the interior of oil bottle 404, but it is preferred that theopening on conduit 412 be at least several inches above the base. Thisinsures that a minimum amount of oil is left within oil bottle 404during an exchange, and thus the oil being exchanged may be sufficientlycooled when mixed with oil in bottle 404. In addition, this providessettling space for any debris that may enter the system. In this way, astandard commercial bottle (i.e., the oil bottle purchased by the userat a retailer) may be used. Alternatively, a specialized bottle, such asone made of nylon, thick-wall HDPE or metal could be utilized and thusmore readily receive hot oil from the engine.

Another inlet/outlet fitting 416 of pump 410 is fluidly coupled to anengine sump 418 via a sump conduit 420. Within sump 418 and connected tosump conduit 420 is a bent tube 422. Bent tube 422 may be inserted intosump 418 through the existing oil drain plug 424 of the engine and issized and angled such that its open end is positioned near the center ofthe oil volume, which is typically near the centerline (or crankshaft)of a vertical shaft engine. This positioning of the bent tube 422reduces the effects that tilting or angling of the engine will have onthe oil level 426 relative to the tube.

In operation, a controller (not shown) onboard the bottle holder 402 orelsewhere on the machine detects whether or not the engine is running Ifthe engine has not been running for a predetermined period of time(e.g., 5 seconds to 5 minutes), a signal is sent to pump 410 viacommunication lines 432 to begin the oil exchange process. This processcomprises pumping oil from oil bottle 404 for a predetermined period oftime (e.g. 1-15 seconds) to transfer a quantity of oil from oil bottle404 to sump 418 (e.g., 4-20 fl. oz.). After this predetermined period oftime has lapsed, the controller then sends a signal to pump 410 toreverse operation and pump oil out of sump 418 of the engine for anotherpredetermined period of time (e.g., 5-30 seconds). The pump 410 willtypically run longer when it is pumping oil out of sump 418 than when itis pumping oil into sump 418 to ensure that the engine oil is maintainedwithin sump 418 at the correct level (i.e., approximately the level ofthe opening on bent tube 422) such that predominantly air is beingpumped out of pump 410. Pump 410 is preferably an electric motor-poweredgear pump that is able to self-prime, pump air, and easily reversepumping direction. However, other pump designs may also be used.Alternatively, the controller may determine that the oil level in sump418 is sufficient by detecting that the current draw of pump 410 hasreached a predetermined low threshold amount, signifying that pump 410is sucking air rather than oil and thus it is safe to turn pump 410 offThe controller could also be configured to allow for a predeterminedwait period between pumping oil into sump 418 and pumping oil out ofsump 418 so as to allow time for the oil to mix. In this way, a singleset of input/output lines can be used between oil bottle 404 and sump418, oil can be interchanged after engine operation, and the user can beassured that sump 418 maintains the correct oil level after each oilexchange operation. In an alternative construction, a single lineextends between the supplemental oil tank and engine. The line wouldthen branch into two separate lines within the engine with one linearranged to draw oil from the engine sump and the second line arrangedto add oil to the engine sump. Check valves could be positioned in eachline to assure the proper flow in each line.

As an alternative to the process described above, it is alsocontemplated that the oil exchange process could be activated when anengine's ignition key is detected to be in the “off” position. Likewise,the process could be activated when the ignition key is detected to bein the “on” position, or the fill cycle could be activated when the keyis in the “off” position and the drain cycle activated when the key isin the “on” position. Another alternative is for there to be auser-actuated switch to allow the operator to determine when they wouldlike the oil exchange process to be activated.

Turning to FIG. 5, a sectional view of an engine sump and portions ofthe oil exchange system in accordance with an exemplary embodiment areshown. Engine sump 502 contains oil 504 that is preferably maintained ata predetermined level. A bent tube 506 is attached to a fitting 508 andconduit 510, wherein fitting 508 is designed to fit into the existingoil drain plug opening 512 of the engine. Bent tube 506 is sized andshaped such that the tube can be easily inserted into the plug opening512 and positioned such that an opening 514 of bent tube 506 is near thecenter of the engine (and the crankshaft) and is substantially alignedwith a preferred oil level within sump 502. Tube 506, fitting 508,and/or conduit 510 are preferably marked to allow the user to determineif bent tube 506 is properly oriented within sump 502. If theorientation of bent tube 506 within sump 502 is not proper, the oillevel maintained may not be sufficient. As FIG. 6 shows, during the oilexchange process, an additional amount of oil 516 is added to the sumpto be mixed with the oil 504 already therein. After a predeterminedperiod of time (or some other predetermined operation), an amount of oilis pumped out of sump 502 such that the level is again maintained at thelevel of the opening 512 of bent tube 506.

Additionally, the configuration shown in FIG. 5 could allow for an “oilchange” operation as opposed to an oil exchange operation, as describedabove. In this “oil change” operation, the fitting 508 and bent tube 506may be clocked or rotated approximately 90 degrees in either direction(for example by a user manipulating a handle provided on the outside ofthe engine that connects to the tube) such that the opening 514 of benttube 506 is rotated or moved to then be located near the base of theinterior of sump 502. In this position, the pump (not shown) can be usedto extract a majority of the oil 504 in sump 502 into the supplementaloil container (not shown). A user-actuated switch could be used totrigger this “oil change” operation, as opposed to the automatedapproach of the oil exchange operation described above. Such an “oilchange” mode would allow for convenient disposal of spent oil, as theuser would not have to access the drain of sump 502 for each oil change,but would instead be able to properly dispose of or recycle the contentsof the supplemental bottle, or dispose of the supplemental bottleentirely. To complete the overall oil maintenance, the user would simplyhave to replace the oil filter and add fresh oil back into the engine,doing so either via a fill tube or again via a supplemental bottle andpump. In another arrangement, a more convenient method for performing acomplete system oil replacement is possible. In this arrangement, asecond conventional drain passage (drain plug or drain hose with cap) onthe engine sump 502, cylinder or cover can be opened to allow the forceof gravity and the head of oil to drain oil out of the engine. The umpis then operated in the proper direction to pump the remaining oil fromthe supplemental oil tank back to the engine for draining In this wayboth quantities of used oil can be easily drained through only onepassage. The old oil filter can be conventionally changed as notedabove.

To replace the drained oil, the tank and sump could each be filledconventionally through respective oil fill openings. Alternately, theengine alone is filled with a sufficient quantity of oil to refill boththe engine and oil tank to proper predetermined levels. The pump is thenoperated in reverse to pump any excess engine oil to the oil tank,thereby leaving the engine at the proper full level. Alternately, oilcould be added only to the supplemental tank and the pump operated toreturn the engine to the proper oil level, either in one timed add/drainpumping process or several smaller add/drain cycles. Pump current drawcould also be used to detect when the engine has been filled properly,by detecting the timing and/or order of high and low current drawassociated with pumping oil and air respectively.

Controller programming and an additional LCD display with user interfacebuttons could provide step-by-step instructions to guide the userthrough the oil change drain and/or refill process and activate the pumpwhen appropriate. The display could also show the oil life percentremaining, hours of operation, when the system has completed a refreshcycle, and other useful user updates. Various methods of establishingoil life percentage are possible. A simple “time only” system may be thesimplest, but time at load or speed and other oil element detectorscould also be used. A sophisticated electromechanical valve system andcontroller could also be added to help automate the drain process.

Referring now to FIG. 7 and FIG. 8, an oil recirculation system inaccordance with another exemplary embodiment is shown. Oil recirculationsystem 600 is illustrated as being implemented on a ride-on zero-turnradius lawnmower, but it is to be understood that oil recirculationsystem 600 could be implemented on any appropriate engine driven deviceincluding a tractor, electricity generator, pressure washer,construction equipment, outdoor power equipment and the like. System 600comprises a supplemental oil tank 602. Supplemental oil tank 602 may beformed of metal, plastic, or any other suitable material. Additionally,the capacity of supplemental oil tank 602 (e.g., 2 gallons) ispreferably larger than the capacity of the engine sump. Supplemental oiltank 602 comprises an easily-accessible oil fill cap 603 capable ofbeing removed such that a user can fill supplemental oil tank 603 withengine oil. In the present embodiment, supplemental oil tank 602 ismounted via one or more tank brackets 604 to a transmission fluidcooling structure 606. In some zero-turn radius mowers, transmissionfluid cooling structures are mounted above an engine and are configuredto accept transmission fluid from one or more hydrostatic transmissionsthat are used to drive the wheels of the mower. As the fluid flowsthrough the cooling structure, it is cooled and then returned to thehydrostatic transmission. In the present embodiment, because coolingstructure 606 is mounted above engine 609, it makes an ideal mountingpoint for supplemental oil tank 602. However, it is to be understoodthat supplemental oil tank 602 may be mounted elsewhere on the mower andmay be used with mowers that do not utilize a transmission fluid coolingstructure.

System 600 further comprises a vent tube 608 which extends from theinterior of supplemental oil tank 602 to the crankcase of engine 609.More specifically, vent tube 608 runs from a point near oil fill cap 603to the engine crankcase so as to maintain a pressure in oil tank 602equal to or nearly equal to the pressure within the running engine'scrankcase. This configuration prevents large pressure differentialsbetween the tank and the engine which may lead to unwanted supplementaloil delivery or extraction via siphoning effects, etc.

Running from the bottom portion of supplemental oil tank 602 is a firstoil hose 611, as shown in FIG. 8. If the supplemental oil tank 602 ismade of a material capable of withstanding high heat (e.g., metal),first oil hose 611 may be coupled to the bottom portion of tank 602 suchthat no portion of first oil hose 611 protrudes into the interior oftank 602. In this configuration, the oil within tank 602 can becompletely drained. On the other hand, if supplemental oil tank 602 isformed of a material not capable of withstanding high heat (e.g.,plastic), first oil hose 611 may protrude a certain amount into theinterior of tank 602 such that a certain level of “cool” oil is alwaysmaintained within tank 602 as described above in reference to FIG. 4.

First oil hose 611 runs from tank 602 to an inlet of an anti-siphonchamber 618, where a second oil hose 612 is coupled to the outlet ofanti-siphon chamber 618. Anti-siphon chamber 618 is configured toprevent oil from being unintentionally siphoned from tank 602 to thesump of engine 609. To achieve this, anti-siphon chamber 618 is designedto have a larger diameter than the diameter of first oil hose 611 andsecond oil hose 612 and is mounted on the mower or other device at apoint higher than the level of oil within tank 602. In addition, thevolume of the anti-siphon chamber 618 that is disposed above the oillevel in the supplemental oil tank 602 should be larger (e.g., 1.2-2times larger) than the internal system volume of the various hoses andother fluid containing devices between the anti-siphon chamber 618 andthe engine sump 602. The anti-siphon chamber 618 has a 180 degree bendat a top portion such that the chamber 618 is located near the uppermostsection of the oil path between tank 602 and engine 609. At least aportion of anti-siphon chamber 618 is mounted above the oil level, evenwhen tank 602 is tipped to an extreme operating angle (e.g., 30degrees). Alternatively, the chamber 618 may have straight or otherangled fittings that position it high within the hose path. Asanti-siphon chamber 618 is higher than the oil level within tank 602,the oil's natural tendency to maintain the same level throughout thesystem (i.e., in both the tank and the hoses) does not cause the oil toflow out of chamber 618 when the flow of oil is not desired.Additionally, the angle of the mower (and subsequently tank 602) doesnot cause oil to flow out of chamber 618 when not desired due to thefact that chamber 618 is mounted at this height.

An electric pump 610 is coupled in-line with second oil hose 612 and isoperational to both pump oil from supplemental oil tank 602 to the sumpof engine 609 and, conversely, to pump oil from the sump to supplementaloil tank 602. Electric pump 610 is preferably a gear pump but may be anyappropriate fluid pump. For example, electric pump 610 could also be apositive displacement pump. A coupling 614 is placed in the oil drainport of engine 609 to fluidly couple oil hose 612 to a sump tubeassembly 616 that is inside the sump of engine 609. Sump tube assembly616 preferable extends upward and into the sump of engine 609 such thatits outlet is near the center of the sump and is a predetermineddistance (e.g. several inches) above the base of the sump. This locationof the outlet of sump tube assembly 616 prevents variations in oil leveldue to the angle of engine 609 when oil is being added to or removedfrom the sump. Additionally, in this embodiment, the outlet of sump tubeassembly 616 preferably sprays the oil laterally away from sump tubeassembly 616 such that the oil added to the sump is better mixed withoil already within the sump, thereby preventing this “new” oil fromeasily being pumped out of the sump during the oil exchange process.

Referring still to FIG. 7 and FIG. 8, system 600 further includes acontrol module 620 that acts to control the timing of an oil exchangesequence to and from tank 602 and the sump of engine 609. Control module620 may be mounted in any appropriate location on the mower or otherdevice. In the embodiment shown in FIG. 8, control module 620 is mountedin a housing near the operator's armrest, and FIG. 7 shows that controlmodule 620 further controls an LED indicator light 622, which isilluminated when the oil exchange sequence is taking place. In someconstructions, a tilt-angle sensor is employed to detect the angle ofthe lawnmower or other components of the system. The tilt-angle sensorprovides data to the controller that is indicative of the angle of thedevice. The controller is then programmed to prevent oil transfers whenthe tilt angle exceeds some predetermined value (e.g., 10 degrees). Theuse of the tilt-angle sensor reduces the likelihood of inaccuratemeasurements or transfers of oil due to the angle of the system.

In the present exemplary embodiment, control module 620 detects when theengine has been shut down for a predetermined period of time (e.g., 6-10seconds). If that period of time has elapsed without the engine beingrestarted, control module 620 instructs pump 610 to begin pumping oilfrom supplemental oil tank 602 into the sump of engine 609 via oil hose612 for another, second, predetermined period of time. When this secondpredetermined period of time has elapsed, the system waits for a thirdpredetermined period of time to allow the oil within the sump to mix andsettle, and then control module 620 instructs pump 610 to reverse andpump oil out of the sump and into the supplemental oil tank 602 via thesame oil hose 612 for a fourth predetermined period of time, wherein thefourth predetermined period of time is longer than the secondpredetermined period of time. In an alternative embodiment, the fourthperiod of time may be equal to the second period of time. With thisconfiguration, an oil exchange process that allows for extendedintervals between general engine service tasks is possible. In anotheralternative embodiment, control module 620 may include electronicsconfigured to sense the angle of supplemental oil tank 602 and engine609 and to prevent pump 610 from cycling when the angle is equal to orgreater than a predetermined amount. This configuration reduces thepotential for under-filling or overfilling the sump of engine 609 due tothe angle of the system. The system may further comprise anextended-performance oil filter 624, which allows for these extendedintervals.

It should be noted that the movement of oil from the supplemental tankto the engine sump and from the engine sump to the supplemental tankoccurs in conjunction. Thus, the order in which the oil is moved is notcritical so long as movements in both directions occurs, therebyassuring that the desired level of oil within the oil sump ismaintained.

The system described herein is described in use with a lawn mower.However, the system could be employed with virtually any system thatincludes an oil-lubricated engine and more particularly anoil-lubricated internal combustion engine. For example, stand-bygenerators (residential and commercial) as well as remote powergenerators (e.g., cell towers, remote pumping stations, etc.) oftenemploy an oil-lubricated engine and would benefit from use of the systemdescribed herein. As such, the invention should not be limited to onlylawn mower applications.

Although the present disclosure has been described with reference toexample embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the defined subject matter. For example, although differentexample embodiments may have been described as including one or morefeatures providing one or more benefits, it is contemplated that thedescribed features may be interchanged with one another or alternativelybe combined with one another in the described example embodiments or inother alternative embodiments. Because the technology of the presentdisclosure is relatively complex, not all changes in technology areforeseeable. The present disclosure described with reference to theexample embodiments and set forth in the following definitions ismanifestly intended to be as broad as possible. For example, unlessspecifically otherwise noted, the definitions reciting a singleparticular element also encompass a plurality of such particularelements.

Various features and advantages of the invention are set forth in thefollowing claims.

What is claimed is:
 1. An oil recirculation system for an internalcombustion engine, the system comprising: an oil sump for storage ofengine oil; a supplemental oil tank configured for storage ofsupplemental engine oil therein; a conduit configured to fluidly couplethe supplemental oil tank and the oil sump such that supplemental engineoil from the supplemental oil tank is selectively delivered to the oilsump and engine oil is selectively extracted from the oil sump anddelivered to the supplemental oil tank; wherein the system is configuredto deliver supplemental engine oil to the oil sump from the supplementaloil tank and extract engine oil from the oil sump to the supplementaloil tank during a predetermined time period.
 2. The oil recirculationsystem of claim 1, wherein the supplemental engine oil is delivered tothe oil sump only when the internal combustion engine is in anonoperational state for a predetermined period of time.
 3. The oilrecirculation system of claim 1 further comprising a controller tocontrol the delivery and extraction of engine oil when the internalcombustion engine is in a nonoperational state.
 4. The oil recirculationsystem of claim 1 further comprising an electric gear pump placedin-line with the conduit to pump supplemental oil from the supplementaloil tank into the oil sump and to pump engine oil out of the oil sumpand into the supplemental oil tank.
 5. The oil recirculation system ofclaim 1 further comprising a positive displacement pump placed in-linewith the conduit to pump supplemental oil from the supplemental oil tankinto the oil sump and to pump engine oil out of the oil sump and intothe supplemental oil tank.
 6. The oil recirculation system of claim 1further comprising an anti-siphon chamber placed in-line with theconduit to prevent unwanted extraction of oil from the supplemental oiltank.
 7. The oil recirculation system of claim 1 further comprising anoil tube within the oil sump and fluidly coupled to the conduit, whereinthe oil tube has an open end not coupled to the conduit that ispositioned within the sump at or near a desired oil level within thesump.
 8. The oil recirculation system of claim 7 wherein the oil tubeenters the oil sump through an engine oil drain port.
 9. The oilrecirculation system of claim 7 wherein the open end of the oil tube ispositioned near a central point in an oil volume of the oil sump.
 10. Anoil recirculation system for an engine having an oil sump that containsa first quantity of oil, the system comprising: a supplemental oil tankoperable to contain a second quantity of oil; a conduit arranged tofluidly connect the supplemental oil tank and the oil sump; and a pumpoperable to at least one of pump oil from the supplemental oil tank tothe oil sump and pump oil from the oil tank to the supplemental oiltank.
 11. The oil recirculation system of claim 10, wherein thesupplemental oil tank includes a polymer container.
 12. The oilrecirculation system of claim 10, wherein the supplemental oil tank ispositioned above the oil sump.
 13. The oil recirculation system of claim12, wherein the supplemental oil tank is operable to deliver oil to theoil sump via a gravity feed.
 14. The oil recirculation system of claim12, wherein the pump is operable to pump oil from the oil sump to thesupplemental oil tank.
 15. The oil recirculation system of claim 10,wherein the supplemental engine oil is delivered to the engine onlyafter the engine is in a nonoperational state for a predetermined periodof time.
 16. The oil recirculation system of claim 10 further comprisinga controller to control the delivery and extraction of engine oil whenthe engine is in a nonoperational state.
 17. The oil recirculationsystem of claim 10 wherein the pump includes an electric gear pumpplaced in-line with the conduit to pump supplemental oil from thesupplemental oil tank into the oil sump and to pump engine oil out ofthe oil sump and into the supplemental oil tank.
 18. A method ofextending the life of an oil supply for an engine, the methodcomprising: providing a first quantity of oil in an oil sump; drawingoil from the oil sump during engine operation to cool and lubricate theengine; periodically adding a second quantity of oil from a supplementaloil tank when the engine is not running; and pumping about the secondquantity of oil from the sump in conjunction with the addition of oilfrom the supplemental oil tank to return the amount of oil in the sumpto about the first quantity.
 19. The method of claim 18, wherein theadding a second quantity of oil occurs only when the engine is in anonoperational state for a predetermined period of time.
 20. The methodof claim 18, wherein the adding a second quantity of oil step occursunder the force of gravity alone.